The genome and proteome of Serratia bacteriophage η which forms unstable lysogens

Background:Serratia marcescensphageηis a temperate unclassified member of theSiphoviridaewhich had beenreported as containing hypermodified guanine residues. Methods:The DNA was characterized by enzymatic digestion followed by HPLC analysis of the nucleosidecomposition, and by DNA sequencing and proteomic analysis. Its ability to form stable lysogens and integrate wasalso investigated. Results:Enzymatic digestion and HPLC analysis revealed phageηDNA did not contain modified bases. Thegenome sequence of this virus, determined using pyrosequencing, is 42,724 nucleotides in length with a mol% GCof 49.9 and is circularly permuted. Sixty-nine putative CDSs were identified of which 19 encode novel proteins.While seven close genetic relatives were identified, they shared sequence similarity with only genes40to69of thephageηgenome, while gp1 to gp39 shared no conserved relationship. The structural proteome, determined bySDS-PAGE and mass spectrometry, revealed seven unique proteins. This phage forms very unstable lysogens withits hostS. marcescens.ISSN:1743-422